Thanks for the info.
FYI: Number 8 above has always been true. It was the same with the PF03 in my '09 JSW. CAN bus is not multi-access. Two "computers" can not both talk on the diagnostic bus at the same time. Polar FIS+ uses the diagnostic bus as does VCDS. More than once I forgot to turn off my FIS+ and got communication errors with VCDS. Luckily its easy to fix (turn off).